zx chassis engine fitting into rev chassis?

[CATillak]

I'm still thinking rings or crank seal. I had a crack in my carb boot last ride and it fluctuated the RPM at idle and ran 200 degrees hotter on that side but never died or hard to start.

If thats the case he should fire it up and spray something flammable around the boots, behind the clutch, see if hes got a leak.

Iv ran cracked carb boots for quite some time and never notived an isuue other than below 4500-5000rpm it sounds like its running on one lung. Does it sound like crap till you open it up? If he had a torn crank seal wouldnt he have some white plugs?? atleast on the PTO.

 

[icr]

Ive ran cracked carb boots for quite some time and never noticed an isuue other than below 4500-5000rpm it sounds like its running on one lung. Does it sound like crap till you open it up? If he had a torn crank seal wouldnt he have some white plugs?? atleast on the PTO.

If it runs like yours the crack is self sealing at high RPMs, mine was more of a hole...the silicone used to install my nitrous nozzles had flaked off, so it was lean all the way through the power band, it never had a chance to close itself like a crack can.

Yes on the seal, it'll cause a lean condition. Sometimes it's not a tear, the seal is old and dried up so it can't expand with the cases when they heat up. This can cause a lean bog so bad the plug color won't change and the engine will die, often feels like it floods out even though the plugs are dry. Like you said the easiest way to test both is spray ether or WD-40 around both areas, especially once the engine is hot and/or bogging.

 

[arctic-moose]

Hard Starting

I had a summit 700 that would do the same thing. It ended up being compression in the cylinders. When the engine was cold, the rings were compressed tight around the piston, but once I turned the motor over 10-20 times it would warm up and the rings expanded in the cylinders and would finally create enough compression to fire and stay running. The compression numbers with the motor cold were really low, but once it was started and warm, the compression was in the good range. Some new pistons and rings and a good hone on the cylinders and I was back on the snow. Hopefully it is something easier, but check the compression. Better to do the top end in the garage than on the back side of a moutain. Glad to hear the motor fits though.

 

[rev440alaska]

I dont think its compression because it will run fine randomly whether the engine is warm or cold. Sometimes it will randomly bog and run on only the left cylinder. I am about to check the compression though as soon as Im done posting this.

 

[IQRIDR]

I dont think its compression because it will run fine randomly whether the engine is warm or cold. Sometimes it will randomly bog and run on only the left cylinder. I am about to check the compression though as soon as Im done posting this.

Compression check, then check your coil and plug wires

 

[aksnow]

carbs

check the choke and just clean the carbs in general....I had a corroded choke plunger that made a sled bog and run like crap intermittently......just a thought

 

[rev440alaska]

my compression tester is reading 30 psi in both cylinders... although it starts up and runs fine so obviously my compression reader is broken. But I did go through the carbs and clean everything, drained the gas and put fresh gas in, checked the choke wires, checked every wire on the sled for good connection. Im just going to have to take it out again and see what happens I guess.

 

[icr]

put some isoheet in it too, just for fun.

 

[rev440alaska]

lol, will do! I'll make sure its the red bottle too...hate to have those gas lines get eaten away.